Right now, the <gender>_focus tags (male_focus, female_focus, intersex_focus, ambiguous_focus) are massively undertagged - a search for solo_focus ~male_focus ~female_focus ~intersex_focus brings up only 87 pages of results, while solo_focus -male_focus -female_focus -intersex_focus brings up 750+.
What can be done about this?
There's a few obvious places where progress can be made - for instance, solo_focus -male_focus -female_focus -intersex_focus male/female turns up 512 pages of results, virtually all of which are clear instances of female_focus - clearly far too many for me to imagine trying to tag them by clicking, waiting for the page to load, scrolling down, copy-pasting in female_focus, hitting enter, etc., but I understand that privileged users have some more efficient way to add tags - would that make this tractable?
That leaves another 551 pages, according to solo_focus -male_focus -female_focus -intersex_focus -male/female.
solo_focus -male_focus -male/female -female_focus -intersex_focus female accounts for 263 of those, again, virtually all female. (faceless_females and disembodied_vaginas being much rarer than faceless_males and disembodied_penises, and disembodied_hands being male by default, so if a solo_focus image contains a female she's very likely the focus)
solo_focus -male_focus -female_focus -intersex_focus -male/female male/male turns up 116 more pages of results, virtually all of which are clearly male_focus.
And solo_focus -male_focus -female_focus -intersex_focus intersex turns up 30 more pages which are virtually all untagged intersex_focus.
Which leaves only 142ish pages that would require significantly more manual examination. (There's some overlap between those numbers, so it's a little more than 142, but not much - only a couple pages)
Updated by SnowWolf